This invention relates to a lighting device for a vehicle in which a lens is attached to a reflector in a fitted manner, and more particularly to a lighting device construction suited for use in a vehicle lighting device in which its dimension in a direction of an optical axis is limited.
One example of a vehicle lighting device, used in a vehicle such as an automobile, is a combination lamp having a plurality of lamps integrally combined together. For example, FIG. 2 is a horizontal cross-sectional view of a combination lamp in which a front turn signal lamp FTSL is integrally incorporated in a fog lamp FGL. A lighting chamber is formed by a lighting device body 1 and a lens (outer lens) 2 attached to a front open portion (front opening) 11 of this body 1. A plurality (two in this example) of reflectors 3 and 5 are provided within the lighting device body 1. An electric bulb 4 is attached to the reflector 3 which reflects light emitted from the energized electric bulb 4. The light then illuminates the front of an automobile through the outer lens 2 and, thereby, lamp 4 functions as the fog lamp FGL. An inner lens 6, of an amber color, is attached to a front open portion (front opening) of the other reflector 5, which is of a smaller size than is reflector 3. An electric bulb 7 is mounted on a rear portion of the reflector 5 which reflects light emitted from the energized electric bulb 7. The light is converted into an amber color through the inner lens 6, and further travels toward the front of the automobile through the outer lens 2 and, thereby lamp 7 functions as the front turn signal lamp FTSL.
In such a combination lamp, the outer lens 2 is attached to the front open portion 11 of the lighting device body 1 by a mounting structure, employing a sealant, in order to maintain a sealed condition within the lighting chamber. Therefore, the inner lens 6 can be attached to the reflector 5 of the front turn signal lamp FTSL, mounted within the sealed lighting chamber, by the use of a non-waterproof-type mounting structure employing an engagement structure having no sealing function. Therefore, in. the conventional construction as shown in FIG. 8, a plurality of engagement holes 58 are formed in a substantially-cylindrical peripheral wall of the front opening 51 in the reflector 5. Further, the plurality of engagement holes 58 are spaced from one another in the circumferential direction. An annular flange 61 is formed at a peripheral edge of the inner lens 6, and a plurality of elastic legs 66 are formed on and project rearwardly from this annular flange 61. The plurality of elastic legs 66 also are spaced from one another in the circumferential direction. An engagement projection 67, for fitting in a respective engagement hole 58, is formed at a distal end of each elastic leg 66. When the annular flange 61 of the inner lens 6 is fitted into the front opening 51 in the reflector 5, the elastic legs 66 are elastically deformed radially inwardly and are inserted into the front opening 51. Then, when the elastic legs 66 are inserted into their respective predetermined positions, the engagement projections 67 are engaged respectively in the engagement holes 58 by a radially outwardly-acting elastic restoring force of the elastic legs 66. With the above-described arrangement, the inner lens 6 is attached to the reflector 5.
In this construction of the lighting device, particularly with respect to the engagement structure for the reflector 5 and the inner lens 6 which jointly form the front turn signal lamp FTSL, when the dimension of the inner lens 6 in the direction of the optical axis, that is, the thickness of this lens, is limited, the length of the elastic legs 66 is also limited. Particularly when it is desired to reduce the overall thickness of the combination lamp so as to achieve a thin design, the dimensions of the reflector 5 and the inner lens 6 of the front turn signal lamp FTSL in the direction of the optical axis can not be increased since the dimension of the lighting chamber is limited. Therefore, the length L12 of the elastic legs 66 must be reduced. The elastic legs 66, of resin, are molded integrally with the inner lens 6, and an elastic nature is imparted to the elastic legs 66 by the elasticity of this resin. Therefore, when the length L12 of the elastic legs 66 is reduced, the elastic legs 66 can not adequately be elastically deformed. Therefore, the conventional construction encounters problems in that the engagement projections 67 sometimes fail to be engaged in the respective engagement holes 58, thus making it difficult to attach the lens 6 to the reflector 5. Further, when trying to forcibly achieve this engagement, the elastic leg or legs 66 may be broken, so that the lamp becomes defective.
It is an object of this invention to provide a lighting device for a vehicle in which the length of elastic legs can be designed freely so that the elastic legs adequately can be elastically deformed. Further, it is an object of the invention to provide, on such elastic legs, engagement projections which can be suitably engaged in respective engagement holes, thereby enabling a lens to be positively and easily attached to a reflector.
According to the invention, there is provided a lighting device, for a vehicle, including: a reflector having a front open portion and engagement holes formed in a peripheral edge portion of the front open portion, and a lens attached to the front open portion, wherein the lens includes engagement projections which are respectively engaged in the engagement holes, thereby supporting the lens on the reflector; the lens further includes cantilever-type elastic legs formed on those portions of the lens which are to be opposed to respective engagement holes in the reflector, wherein the cantilever-type legs extend in a direction of a periphery of the lens, and the engagement projections are formed at respective distal end portions of the elastic legs. The engagement holes in the reflector are provided at regions spaced from one another in a direction of a periphery of the reflector. Also, the elastic legs, as well as the engagement projections of the lens, are provided at regions spaced from one another in the direction of the periphery of the lens so that the engagement holes are respectively opposed to the elastic legs as well as opposed to the engagement projections. Preferably, a cylindrical flange of a substantially cylindrical shape, for insertion into the front open portion of the reflector, is formed integrally at a peripheral edge of the lens. The elastic legs are formed as a result of forming slits in a peripheral wall of the cylindrical flange, and the engagement projections are formed on and project radially outwardly from outer surfaces of respective elastic legs. A length of each of the elastic legs, in the direction of the circumference of the cylindrical flange, is larger than a length of the cylindrical flange in a direction of an optical axis of the lighting device.
In the invention, the elastic legs formed on the lens extend in the direction of the periphery of the lens and, therefore, even when the lens is formed with a thin design, the length of the elastic legs in the circumferential direction is not limited. Therefore, each elastic leg can have a length that allows it to be sufficiently elastically deformed so as to fit the engagement projection into the engagement hole. And the engagement projection can be positively and easily engaged in the engagement hole. Even if one tried to forcibly engage the engagement projection in the engagement hole, the elastic leg will not break and, therefore, a defective assembly of the front turn signal lamp is prevented.